We knew Elton John and David Furnish’s 4-month-old son was on a breast-milk diet — and now we know how!

Elton John, 64, and his partner David Furnish, 48, reveal that their 4-month-old son Zachary‘s biological mother has been sending pumped breast milk to the family via FedEx!

“The baby’s been brought up in Los Angeles for the first four months so we’ve had the breast milk FedExed from where she is to Los Angeles every day,” explains Elton during a recent interview with Barbara Walters, adding that his son’s surrogate will always be involved in his upbringing. “She and her family will still be a part of our lives growing up.” That’s wonderful!

And now that the secret is out about where the breast milk comes from, we’re hoping Elton and David will reveal which one of them is Zachary’s biological father — and luckily, they plan to!

“Zac will have to know for his medical records,” Elton says. “If it’s David, I’d be very proud. It wouldn’t matter to me – and vice versa.”

By the looks of it, we’re pretty sure we know who the dad is — Zachary is the spitting image of Elton!